Winds increased yesterday and drifted 3-6” of new snow into slabs that were easily triggered by skiers, breaking up to 6 inches deep and 20-50 feet wide. Similar avalanches are possible for a person to trigger today, and the potential size could be larger than yesterday due to winds continuing to drift snow and grow slabs overnight. Steer clear of recently formed drifts on steep slopes, especially where a slide would have high consequences like above trees, cliffs or a confined gully.
Wind slabs might break wider, or be easier to trigger for longer than usual, due to resting on a recently formed weak layer of sugary facets or firm crusts.
Yesterday morning snowfall favored the Bridger Range and Hyalite with 3-6” of low density snow. Winds increased through the day and drifted the new snow into slabs that were easily triggered by skiers, breaking up to 6 inches deep and 20-50 feet wide (Divide peak observations, Mt. Blackmore obs. 1, Mt. Blackmore Obs. 2, Bridgers observation). Similar avalanches are possible for a person to trigger today, and the potential size could be larger than yesterday due to winds continuing to drift snow and grow slabs overnight. Yesterday’s snow and wind slabs fell on layers of weak facets and firm crusts which contributed to them being more reactive, and means they might remain unstable longer than usual. Watch for cracking across the snow surface as a clear sign the new snow or wind drifts are still unstable. Your safest bet is to steer clear of recently formed drifts on steep slopes, especially where a slide would have high consequences like above trees, cliffs or a confined gully. The avalanche danger is MODERATE in the Bridger Range and Northern Gallatin Range.
The rest of the forecast area received 0-2” of snow yesterday. Strong winds over the last 24 hours drifted any soft snow into thin slabs. Wind slabs will be small, isolated in distribution and only a hazard in high consequence terrain, such as above cliffs where a fall would be dangerous or deadly if knocked off your feet. Yesterday snowmobilers in the southern Madison Range triggered a 3” thick drift that broke about 50’ wide (observation). If you find a small drift in “extreme” or high consequence terrain, expect it to be reactive due to sitting on weak snow or a firm crust, and find a route around it. Avalanches are unlikely other than a few small wind slabs, and avalanche danger is LOW near Cooke City, West Yellowstone, Big Sky and Island Park. Follow normal safe travel protocols of only exposing one person at a time to steep slopes, having a partner watch from a safe spot, and carrying proper rescue gear.
